The LNB has four outputs, each carrying one of
the four sets of signals needed by a distribution head-end. The
black tubing pushed over the ‘f’ connectors is actually
heat-shrink, and if had been warmed it would have shrunk and conformed
to the shape of the connector, making quite a good weatherproof
seal. But the installer didn’t bother, and in fact the plugs
and cable were both affected by water, which is how I came to take
this picture.